An image up-scaling, also considered an up-sampling or up-conversion, process may increase the number of pixels in a dimension of an image. Typical up-scaling processes may not provide visually satisfactory results when applied to an image containing graphical elements, also considered graphics, graphics elements, graphical regions, graphical areas, graphics areas and graphics regions. It may be desirable for an up-scaling process to produce an up-scaled image of equal, or increased, visual quality as the original image, even when the content of the image comprises graphical elements. Exemplary graphical elements may comprise text, signs, icons, visual elements generated by two-dimensional (2D) computer graphics systems, visual elements generated by three-dimensional (3D) computer graphics systems and other elements ideally comprising a step edge.
The graphical elements in an image may convey important semantic information about the image and may be more likely to draw a viewer's attention than the other portions of the image, considered non-graphical areas, non-graphics areas, non-graphical regions, non-graphics regions and other terms indicating that an image portion does not comprise graphical elements. Consequently, a viewer may be more likely to notice the clarity and sharpness, or lack thereof, of an up-scaled graphical region, which may influence their perception of the entire image. On the other hand, viewers may pay less attention to non-graphical image regions, which may be less salient. Non-graphical image regions typically do not contain step edges. Scene background regions may be considered non-graphical image regions. Non-graphical image regions may be captured optically or generated by computer graphics methods, and non-graphical image regions may comprise natural scenes, rendered scenes, objects and other scenes in which the edges are not sharp, step edges.
Conventional image up-scaling methods often introduce visible artifacts in a graphics region, which may reduce the perceived visual quality of the up-scaled image. Region-based up-scaling processes may be desirable for these reasons.